The invention relates to doors and other structural panels formed from two sheets separated by a frame, sometimes with a foam or other core between the sheets.
Examples of doors made in this way may be found in U.S. Pat. No. 4,550,540 and 4,864,789 issued to Thorn. In some previous designs, the sheets have been glued to a frame, which forms the edges of the panel. See especially U.S. Pat. No. 4,864,789. Gluing the sheets to the frame members is a relatively costly manufacturing operation. There is therefore a need for a sandwich-type panel which can be assembled simply and without gluing the sheets to the frame members.
In some cases, the space between the sheets is filled with foam in a liquid state, which then hardens into a solid foam core. In storm doors, which have an opening for a window, it has been found that the liquid foam tends to leak into the window frame area, which necessitates clean up work, which increases manufacturing costs. There is therefore a need to control the flow of the foam in order to minimize such leakage.
In some uses, the solid foam core can provide sufficient structural integrity so that framing members would not be needed on all sides, except for the need to provide an enclosed chamber into which to introduce the liquid foam. There is a need for a way to introduce the foam without using unnecessary framing members which add weight and cost.